The present invention is directed to a foundation system for supporting an architectural structure and, in particular, to a frost-protected foundation system.
A known frost-protected shallow foundation 10 is a practical alternative to a deeper, more-costly known full foundation 8 in cold regions with seasonal ground freezing and the potential for frost heave (FIGS. 1 and 2). Shallow foundation 10 may include a combination slab 12 and footing 14 which are made of concrete that is made concurrently from the same concrete pour as shown. Alternatively, the foundation may be poured separately and utilities, such as rough plumbing, wiring conduit, or the like, laid out before the slab is poured. An insulation sheet 16 raises soil temperature and the frost depth around the building thereby allowing foundation depths as shallow as sixteen inches for many areas. The known shallow foundation is thus an improvement over the full foundation.
However, the foundation must still be formed using concrete forms which is labor intensive. Also, the foundation is cured and inspected prior to backfilling and the backfilling completed prior to installing plumbing. The plumbing is inspected prior to pouring the concrete floor. All of the delays associated with these sequential steps add further to the cost of the structure. Also, resistance to heat transmission is limited to the characteristics of insulation sheet 16.